1 10.3 FOURMILE EAST 2 3 4 10.3.1 Background and Summary of Impacts 5 6 7 10.3.1.1 General Information 8 9 The proposed Fourmile East SEZ has a total area of 3,882 acres (15.7 km2) and is located 10 in Alamosa County in south-central Colorado (Figure 10.3.1.1-1). In 2008, the county population 11 was 15,783, while the four-county region surrounding the SEZ—Alamosa, Conejos, Costilla, and 12 Rio Grande Counties—had a total population of 39,759. The largest nearby town is Alamosa, 13 with an estimated 2008 population of 8,745, which is located about 13 mi (21 km) to the west on 14 U.S. 160. This highway lies about 0.6 mi (1 km) south of the SEZ, while CO 150 runs north- 15 south through the eastern portion of the SEZ; Great Sands Dunes National Park is located about 16 9 mi (14 km) north of the SEZ on CO 150. The SLRG Railroad serves the area. The nearest 17 public airport is San Luis Valley Regional Airport located 12 mi (19 km) west of the SEZ in 18 Alamosa. Santa Fe, New Mexico, lies about 120 mi (193 km) to the south, and Denver, 19 Colorado, lies about 170 mi (31 km) to the northeast. 20 21 An existing 69-kV transmission line lies about 2 mi (3 km) to the south, and a 230-kV 22 line lies about 8 mi (13 km) to the north of the SEZ. It is assumed that a new transmission line 23 would be needed to provide access from the SEZ to the transmission grid (see Section 10.3.1.2). 24 As of February 2010, there were no pending solar project applications on the SEZ. 25 26 The proposed Fourmile East SEZ lies in the eastern San Luis Valley, part of the San Luis 27 Basin, a high-elevation (approximately 8,000 ft [2,440 m]) basin between two large mountain 28 ranges. The San Juan Mountains to the west and the Sangre de Cristo Range to the east form the 29 rim of the basin. The proposed SEZ lies on a flat alluvial fan formed in the basin. There are no 30 developments on the land, which is currently used for grazing, nor is there any standing surface 31 water. Scrubland vegetation reflects the arid climate, which produces an annual average rainfall 32 of about 8 in (20 cm). Large groundwater reserves underlie the area in several aquifers. Little 33 commercial or industrial activity exists in the surrounding area, while some agricultural areas lie 34 to the southeast. 35 36 The proposed Fourmile East SEZ and other relevant information are shown in 37 Figure 10.3.1.1-1. The criteria used to identify the SEZ as an appropriate location for solar 38 energy development included proximity to existing transmission lines or designated corridors, 39 proximity to existing roads, a slope of generally less than 2%, and an area of more than 40 2,500 acres (10 km2). In addition, the area was identified as being relatively free of other types 41 of conflicts, such as USFWS-designated critical habitat for threatened and endangered species, 42 ACECs, SRMAs, and NLCS lands (see Section 2.2.2.2 for the complete list of exclusions). 43 Although these classes of restricted lands were excluded from the proposed Fourmile East SEZ, 44 other restrictions may be appropriate. The analyses in the following sections address the affected 45 environment and potential impacts associated with utility-scale solar energy development in the 46 proposed SEZ for important environmental, cultural, and socioeconomic resources. Draft Solar PEIS 10.3-1 December 2010 1 2 FIGURE 10.3.1.1-1 Proposed Fourmile East SEZ Draft Solar PEIS 10.3-2 December 2010 1 10.3.1.2 Development Assumptions for the Impact Analysis 2 3 Maximum development of the proposed Fourmile East SEZ was assumed to be 80% of 4 the total SEZ area over a period of 20 years, a maximum of 3,105 acres (12.6 km2). These values 5 are shown in Table 10.3.1.2-1, along with other development assumptions. Full development of 6 the Fourmile East SEZ would allow development of facilities with an estimated total of 345 MW 7 of electrical power capacity if power tower, dish engine, or PV technologies were used, 8 assuming 9 acres/MW (0.04 km2/MW) of land required, and an estimated 621 MW of power if 9 solar trough technologies were used, assuming 5 acres/MW (0.02 km2/MW) of land required. 10 11 Availability of electric transmission facilities from SEZs to load centers will be an 12 important consideration for future development in SEZs. For the proposed Fourmile East SEZ, 13 the nearest existing transmission line is a 69-kV line 2 mi (3.2 km) of the SEZ. It is possible that 14 a new transmission line could be constructed from the SEZ to this existing line, but the 69-kV 15 capacity of that line would be inadequate for 345 to 621 MW of new capacity (note: a 500-kV 16 line can approximately accommodate the load of one 700-MW facility). At full build-out 17 capacity, it is clear that substantial new transmission and/or upgrades of existing transmission 18 lines would be required to bring electricity from the proposed Fourmile East SEZ to load centers; 19 however, at this time the location and size of such new transmission facilities are unknown. 20 Generic impacts of transmission and associated infrastructure construction and of line upgrades 21 on various resources are discussed in Chapter 5. Project-specific analyses would need 22 23 TABLE 10.3.1.2-1 Proposed Fourmile East SEZ—Assumed Development Acreages, Maximum Solar MW Output, Access Roads, and Transmission Line ROWs Distance and Assumed Distance to Capacity of Distance to Total Acreage Maximum SEZ Nearest Nearest Assumed Area Nearest and Assumed Output for State, U.S., Existing of Transmission BLM-Designated Developed Acreage Various Solar or Interstate Transmission Line ROW and Transmission (80% of total) Technologies Highway Line Road ROW Corridore 3,882 acres and 345 MWb Adjacent 2 mid and 61 acres and Adjacent/ 3,105 acresa 621 MWc (CO 150) 69 kV 0 acres Throughf a To convert acres to km2, multiply by 0.004047. b Maximum power output if the SEZ were fully developed using power tower, dish engine, or PV technologies, assuming 9 acres/MW (0.04 km2/MW) of land required. c Maximum power output if the SEZ were fully developed using solar trough technologies, assuming 5 acres/MW MW (0.02 km2/MW) of land required. d To convert mi to km, multiply by 1.609. e BLM-designated corridors are developed for federal land use planning purposes only and are not applicable to state-owned or privately owned land. f A BLM locally designated corridor covers the entire proposed Fourmile East SEZ. 24 Draft Solar PEIS 10.3-3 December 2010 1 to identify the specific impacts of new transmission construction and line upgrades for any 2 projects proposed within the SEZ. 3 4 To provide as complete an analysis of impacts of solar development in the SEZ as 5 possible, it was assumed that, at a minimum, a transmission line segment would be constructed 6 from the proposed Fourmile East SEZ to the nearest existing transmission line in order to 7 connect the SEZ to the transmission grid. This assumption was made without information on 8 whether the nearest existing transmission line would actually be available for connection of 9 future solar facilities, and without assumptions about upgrades of the line. Establishing a 10 connection to the line closest to the Fourmile East SEZ would involve the construction of about 11 2 mi (3.2 km) of new transmission line outside of the SEZ. The ROW for this transmission line 12 would occupy approximately 61 acres (0.25 km2) of land, assuming a 250-ft (76-m) wide ROW, 13 a typical width for such a ROW. If a connecting transmission line were constructed to a different 14 location in the future, site developers would need to determine the impacts from construction 15 and operation of that line. In addition, developers would need to determine the impacts of line 16 upgrades if they were needed. 17 18 Existing road access to the proposed Fourmile East SEZ should be adequate to support 19 construction and operation of solar facilities, because CO 150 runs within the eastern boundary 20 and U.S. 160 runs less than 1 mi (2 km) to the south of the SEZ. Thus, no additional road 21 construction outside of the SEZ is assumed to be required to support solar development, as 22 summarized in Table 10.3.1.2-1. 23 24 25 10.3.1.3 Summary of Major Impacts and Proposed SEZ-Specific Design Features 26 27 In this section, the impacts and proposed SEZ-specific design features assessed in 28 Sections 10.3.2 through 10.3.21 for the proposed Fourmile East SEZ are summarized in 29 tabular form. Table 10.3.1.3-1 is a comprehensive list of impacts discussed in these sections; 30 the reader may reference the applicable sections for detailed support of the impact assessment. 31 Section 10.3.22 discusses potential cumulative impacts from solar energy development in the 32 proposed SEZ. 33 34 Only those design features that are specific to the Fourmile East SEZ are included 35 in Sections 10.3.2 through 10.3.21 and in the summary table.